The refinishing of valve seats on an internal combustion engine is normally accomplished utilizing either a grinding wheel or a valve cutter employing a plurality of carbide cutting elements. This latter technique, and specifically the equipment for permitting refinishing of the valve seats, is disclosed in U.S. Pat. Nos. 3,354,528 and 3,391,604. The use of this latter-mentioned technique, namely the employment of carbide cutting elements having a plurality of teeth thereon for refinishing a valve seat, is particularly desirable since it is believed to result in a more uniform refinishing of the valve seat, while permitting the refinishing to be performed in a more efficient manner. Further, with the increased usage of nonleaded fuel in vehicle engines, the higher temperatures encountered in the engines require that the valve seats be made of even harder materials so that refinishing of the valve seats becomes even more difficult, which in turn makes the use of carbide cutters (in contrast to grinding) much more attractive for the refinishing of the valve seats. However, the use of valve seat reconditioning equipment employing carbide cutters has been restricted by the difficulty in manufacturing the carbide cutters. These carbide cutters, prior to the present invention, have been conventionally manufactured on an individualized and manual basis. That is, the cutting of the grooves required that the cutter be manually moved and reclamped in the desired position so as to permit each groove to be ground in the cutter. This is obviously extremely time consuming and laborious, and in addition prevents the cutters and particularly the teeth thereon from having a high degee of uniformity in view of the tolerances and errors introduced by the manual manipulations. The carbide cutters produced by this technique have thus not only possessed a degree of nonuniformity, but have also been extremely costly. This has also prevented the manufacture of cutters on a mass scale.
Accordingly, the present invention relates to an improved grinding machine for permitting the automatic manufacture of carbide cutters of this type, which machine overcomes the disadvantages associated with the prior manufacturing techniques explained above. More specifically, the present invention relates to an improved grinding machine for permitting the substantially automatic forming of carbide cutters which not only have a higher degree of uniformity, but which can be manufactured more efficiently and at a much more rapid rate.
The object of the present invention, namely an improved grinding machine as aforesaid, is accomplished by providing a grinding machine with a swingable carriage having a rotatable grinding wheel supported thereon, which grinding wheel is rotatable about an axis which is spaced from the pivot axis of the carriage. A feeding mechanism supplies a carbide element into a grinding region whereby the element is cut by the grinding wheel so as to form grooves thereacross. The feeding mechanism, which moves the element at an angle of approximately 45.degree. relative to the rotational axis of the grinding wheel, advances the element toward the grinding wheel with an intermittent steplike movement which is synchronized with the swinging movement of the carriage. The grinding wheel swings across the element and forms a groove therein, whereupon the element is then stepped forward a preselected amount so that the next swinging movement of the grinding wheel causes the formation of a further substantially parallel groove therein, whereby a cutting tooth is formed between adjacent grooves. This process is continued until the selected surface of the element has a plurality of teeth formed thereon.
Other objects of the invention will be apparent to persons familiar with this technology upon reading the following specification and inspecting the accompanying drawings.